The Internet allows for vast amounts of information to be communicated over any number of interconnected networks, computers, and network devices. Typically, information or content is located at websites on one or more servers, and a user can retrieve the content using a user agent, such as a web browser, running on a client device. For example, the user can input a webpage address into the web browser or access a web link, which sends requests to a server to access and provide the content on the respective website. This type of communication is commonly referred to as “web browsing.”
As web pages have become more complex, a common website may contain hundreds of objects on its web pages. Such objects may include text, graphics, images, sound, etc. The web pages may also have objects located across multiple servers. That is, one server may provide dynamic content (e.g., content that remembers the last books ordered by a user) for a web page, whereas other servers may provide static but rotating content such as an advertisement, and still others provide the static content of the site. As such, before a user can view a web page, hundreds of objects may require downloading from multiple servers. Each server, however, may take a different amount of time to service a request for an object contributing to latency. Thus, the latency for each server may vary with different levels of magnitude, e.g., one server may respond in milliseconds whereas another server may respond in seconds.
When the World Wide Web was first introduced, much of the content was static. Now, a web page is typically accessed by downloading an HTML file that is pointed to by a URL. This file may reference many other objects, including scripts (e.g. JavaScript, Cascading Style Sheet), images (e.g. GIF, JPEG, PNG, BMP), and application content (e.g. Shockwave Flash, Java Applets). Because web pages have become more personalized and are updated more frequently, current caching models for HTTP begin to fail. Thus, the current cache models cannot efficiently handle these dynamic and unique web pages.